1. ¹Department of Genetics, University of Washington, Seattle, Washington, 98195, USA
2. ²Collateral Therapeutics, Inc., San Diego, California, 92130, USA
3. ³VA San Diego Healthcare System and Department of Anesthesia, University of California at San Diego, San Diego, California, 92161, USA
4. ⁴Berlex Biosciences, Richmond, California, 94804, USA
5. ⁵VA San Diego Healthcare System and Department of Medicine, University of California at San Diego, San Diego, California, 92161, USA

Correspondence: Robert E Braun, Fax: (206) 543-0754. E-mail: braun@u.washington.edu.

^*Present address: Research Institute of Molecular Pathology (IMP), Vienna A-1030, Austria

Received 4 June 2001; Accepted 18 October 2001.

Abstract

The possibility of inadvertent exposure of gonadal tissue to gene therapy vectors has raised safety concerns about germline infection. We show here that the receptor for coxsackie B viruses and adenoviruses 2 and 5 (CXADR) is expressed in mouse germ cells, suggesting the possibility that these viruses could infect germ cells. To directly assess the risk of germline infection in vivo, we injected an adenovirus carrying the germ-cell-specific protamine promoter fused to the bacterial lacZ reporter gene into the left ventricular cavity of mice and then monitored expression of the reporter gene in germ cells. To differentiate between infection of stem cells and differ-entiating spermatogenic cells, we analyzed expression of the reporter cassette at different times after viral delivery. Under all conditions tested, mice did not express the Escherichia coli -galactosidase protein in developing spermatids or in mature epididymal spermatozoa. Primary germ cells cultured in vitro were also refractory to adenoviral infection. Our data suggest that the chance of vertical germline transmission and insertional mutagenesis is highly unlikely following intracoronary adenoviral delivery.